To maintain costs as low as possible, EP printers are now designed to allow as much user maintenance as possible. To this end, dry toner EP printers enable a user to replace an exhausted toner cartridge with a new toner cartridge which also contains an entirely new organic photoconductor-coated drum and related actuating mechanisms. EP printers which employ liquid toners are provided with refillable toner reservoirs, thus requiring the user to replenish the inprinter reservoir from a liquid toner supply. The user is thus exposed to possible spillage, vapors, and with color printers, the possibility that a wrong color toner will be loaded into a reservoir.
In copending U.S. patent application, Ser. No. 08/139,956, filed Oct. 20, 1993, now U.S. Pat. No. 5,396,316, (Attorney docket no. 1093459-1), entitled "User-Replaceable Liquid Toner Cartridge With Integral Pump And Valve Mechanisms", a replaceable toner cartridge is described which includes an integral pump connected to a toner supply reservoir and a mechanical coupling that automatically receives a pump actuator when the liquid toner cartridge is inserted into an EP printer. The disclosed liquid toner cartridge structure enables replacement of the pump each time the liquid toner cartridge is replaced, thereby replacing a failure-prone part and providing for more reliable operation of the EP printer. A further valve is connected to an output from the pump and communicates with an external wall of the toner cartridge where it connects to a fluid fitting in the receptacle in the EP printer. The fluid fitting automatically operates the valve in the cartridge and enables liquid toner flow from the cartridge's reservoir into the receptacle's fluid fitting. Even though the fitting is a "dripless" coupling, its external surface is liquid-toner coated when the cartridge is removed from the EP printer. Such toner can stain a user's hands and/or clothing and requires a level of care in handling which many customers are not willing to exert.
The prior art has attempted to solve the toner contamination problem by incorporating a door/shutter arrangement into a coupling surface of a replaceable toner cartridge. Such an arrangement enables a user with finger pressure, to open the door-shutter and to access the toner-stained portion of the cartridge's fluid coupling.
Accordingly, it is an object of this invention to provide an improved, user-replaceable liquid toner cartridge.
It is another object of this invention to provide an improved, user-replaceable liquid toner cartridge with a mechanism which prevents liquid toner from being present on an external surface of the cartridge when it is being handled by a user.
It is still another object of this invention to provide a user-replaceable toner cartridge that includes a means for sealing a toner access valve, the means for sealing being inexpensive and positioned in a wall of the cartridge.